mineral

Polished agate (likely plume or moss agate)

Chalcedony, microcrystalline quartz (SiO₂), with iron-oxide and possible chlorite inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent brown, gray, cream, and greenish layers with waxy to vitreous luster. Quartz has trigonal crystal structure, but the specimen is cryptocrystalline and lacks visible cleavage; curved bands and botryoidal contours are characteristic.

Identified September 11, 2026More mineral →

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At a glance

Common name: Polished agate (likely plume or moss agate)
Scientific name: Chalcedony, microcrystalline quartz (SiO₂), with iron-oxide and possible chlorite inclusions
Category: mineral
Identified: September 11, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a small common polished specimen; $30–$100+ if the pattern, translucency, carving, or provenance is exceptional.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Formed when silica-rich groundwater repeatedly filled cavities in volcanic rock, depositing chalcedony and inclusions in layers. Agate formation commonly dates from the Cenozoic to Paleozoic depending on locality.

Uses & applications

Used for cabochons, carvings, ornaments, beads, and collectible polished specimens; its toughness also suits small decorative objects.

Geological facts

The organic-looking patterns are natural mineral growth, not fossils. Brown coloration typically comes from iron oxides, while green areas may reflect chlorite or other minerals.

Field identification & locations

Identify by its waxy translucency, very fine curved banding, conchoidal fracture, and inability to scratch it with a steel knife; quartz should scratch glass. Common sources include Brazil, Uruguay, India, Mexico, and the United States.